c++builder如何调用vc++MFC DLL 中带有参数的函数（急！！！ 在线等）

[syy64]

程序如下：
h文件：

//---------------------------------------------------------------------------

#ifndef Unit1H
#define Unit1H
//---------------------------------------------------------------------------
#include <Classes.hpp>
#include <Controls.hpp>
#include <StdCtrls.hpp>
#include <Forms.hpp>
#include <Dialogs.hpp>
#include <Menus.hpp>
//---------------------------------------------------------------------------
class TForm1 : public TForm
{
__published: // IDE-managed Components
TOpenDialog *ttt;
TMainMenu *MainMenu1;
TEdit *Edit1;
TLabel *Label1;
TPopupMenu *PopupMenu1;
TButton *Button1;
void __fastcall Edit1Change(TObject *Sender);
void __fastcall Button1Click(TObject *Sender);
private: // User declarations
public: // User declarations
__fastcall TForm1(TComponent* Owner);
};
//---------------------------------------------------------------------------
extern "C" __declspec(dllimport) double __stdcall Ex21cSquareRoot(double d);
extern PACKAGE TForm1 *Form1;
//---------------------------------------------------------------------------
#endif

*.cpp 文件：

void __fastcall TForm1::Button1Click(TObject *Sender)
{
int jj;
double d, d1;
// extern "C" __declspec(dllimport) double __stdcall Ex21cSquareRoot(double d);

HINSTANCE h;
FARPROC pp;
// int _stdcall (*t)(void);
// double _stdcall (*t(double))(void);
h=LoadLibrary("ex21c.dll"); //导入库
pp = GetProcAddress(h,"Ex21cSquareRoot"); //指出库中函数的位置
d = 9.0;
// d1 = Ex21cSquareRoot(d);
d1 = pp(d); 这一行编译出错：[C++ Error] Unit1.cpp(42): E2226 Extra parameter in call
// ShowMessage(IntToStr(t()));
FreeLibrary(h);

jj = 2;
}
//---------------------------------------------------------------------------

高手帮帮忙！！！

[ccddff]

在项目里有没有包含文件 ex21c.lib ?

[syy64]

动态调用也需要吗？

[fxly]

楼主的调用步骤太烦杂了，根本不需要那么麻烦！

[syy64]

你能教教我方法吗？

[syy64]

void __fastcall TForm1::Button1Click(TObject *Sender)
{
int jj;
double d, d1;
// extern "C" __declspec(dllimport) double __stdcall Ex21cSquareRoot(double d);

HINSTANCE h;
FARPROC pp;
// int _stdcall (*t)(void);
typedef double _stdcall (*t)(double);
h=LoadLibrary("ex21c.dll"); //导入库
t t1 = (t)GetProcAddress(h,"Ex21cSquareRoot"); //指出库中函数的位置
d = 9.0;
d1 = t1(d);
FreeLibrary(h);

jj = 2;
}
//---------------------------------------------------------------------------
我又将程序改成上面这样，编译到通过了，但运行时，t1为NULL
有谁能帮帮我！，看来周末没法休息啦！

[syy64]

有高手知道吗？

[bocwg]

extern "C" __declspec(dllexport) double __stdcall Ex21cSquareRoot(double d);
dllimport改为dllexport

[childman]

可能是因为Borland的dll跟Microsoft的dll格式不一样的缘故，很有可能是
GetProcAddress(h,"Ex21cSquareRoot"); //没找到Ex21cSquareRoot这个函数，有可能是_Ex21cSquareRoot也说不定，可以用VC自带的那个Dependy.exe看看

[syy64]

问题已仅仅，谢谢各位。

[seajoke]

两种调用方法被你搞混了！
1。extern "C" __declspec(dllimport) double __stdcall Ex21cSquareRoot(double d);
然后直接调用函数 Ex21cSquareRoot(double d);
2。typedef double (_stdcall *pEx21cSquareRoot)(double d);
*.cpp：
pEx21cSquareRoot FEx21cSquareRoot;
FEx21cSquareRoot = (pEx21cSquareRoot)::GetProcAddress( h, "Ex21cSquareRoot");
然后直接调用函数 FEx21cSquareRoot(double d);